CRISPR Core: Sigma-PSC Core

CRISPR/Cas systems have evolved within bacterial and archaeal organisms as a defense against invading viruses and plasmids. Recently, the type II CRISPR/Cas system from the bacterium Streptococcus pyogenes has been engineered to function in eukaryotic cells using two molecular components: a single Cas9 protein and a non-coding guide RNA (gRNA).1-7 The Cas9 endonuclease can be programmed with a single gRNA, directing a